<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div.father{
    width: 200px;
    height: 200px;
    background-color: rgb(219, 68, 101);
    margin-left: 100px;
    margin-top: 100px;
}
div.father div.son{
    width: 100px;
    height: 100px;
    background-color: rgb(56, 248, 207);
    margin-left: 50px;
    margin-top: 50px;
}
  </style>
</head>
<body>
  <div class="father">
    <div class="son"></div>
  </div>
  asfsdf
</body>
</html>